Laboratory drying oven



Feb. 19, 1952 H. w. DIETERT ET AL LABORATORY DRYING OVEN Filed March 28, 1949 FIGJ.

FIG

INVENTORS HARRY W. DIETERT JOHN A. SCHUCH BY RALPH E.STE|NMUEL mm, M? v @521 ATTORNEYS Patented Feb. 19, 1952 UNITED STATES PATENT OFFICE LABORATORY DR-YING OVEN Harry W. Dietert, John A. Schuch, and Ralph E. Steinmueller, Detroit, Mich., assignors tov Harry W. Dietert Company, Detroit, Mich., a corporation of Michigan ApplicationMarch 28, 1949, Serial No. 83,852

vision of means for withdrawing vapors produced.

by the drying operation.

More specifically, it is an object of the present invention to provide in a drier of the character described, an air heating chamber and a drying chamber separated by a partitionstructure composed of spaced air baflles, the baffles being constructed and arranged to provide for an improved fiow of air relative thereto.

It is a further object of the present invention to provide a drier of the character described including an exhaust passage for air and vapor,

which exhaust passage is open to room air to provide for a relatively uniform flow of air through the drier independent of pressure variations in the stack.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings, wherein:

Figure l is a vertical section through the improved drier.

Figure 2 is an enlarged fragmentary section on the line 22, Figure 1.

Figure 3 is a plan view of an air bafile employed intermediate the heating chamber and the drying chamber.

Figure 4 is a fragmentary plan view of another air baflie.

Referring now to the drawings, the drier comprises a main casting having a bottom closure I I, an intermediate inwardly extending supporting flange I 2, and a top flange and guide element l3. Supported in an annular recess at the-top flange I3 is a cylindrical casing l4 provided with a removable top closure or cover IS. The cover 15 is provided at its interior with an annular re-=' cess 16 for the reception of a resilient expandable retaining wire l'! which may be employed to retain a filter H3 in place. The cover. is provided with a plurality of relatively large air inlet openings l9. If desired, means may be provided in the cover l5 or in the upper-portion of the casing M for supporting a material for removing moisture from the air, such forexample as silica gel.

In the upper portion of. the casing-I4;- is an:

electric motor 20 to which is connected a blower 22 of the cycloidal impeller type.

Supported on the flange l2 and retained in position bythe flange and guide element [3, is

,a generally cylindrical construction comprising a heating chamber and a drying chamber. The drying chamber comprises a foraminous support 25 resting on the supporting flange [2, and a cylindrical liner shell 26 preferably formed of stainless steel. The upper end of the shell 26 is in registry with the guide element [3 which surrounds, it in closely fitting relation. The shell 2B is thus spaced inwardly from the side Wall of the casting H3 and provides a dead air space for insulating against. transfer of heat to the casting [0.

Supported on the top of the shell 26 is an air baffle 28, thecentralportion of which, is imperforate as shown and which is provided with a plurality of circumferentially spaced upwardly extending supporting arms 30. The space between the arms 30 provide air passages indicated at 32. Afire screen of a suitable foraminous material is indicated at 34. The fire screen 34 is attached at its center to the center of the air bafile 28, the connection in this instance being illustrated as provided by a rivet 36. The peripheral edge of the fire screen 34 rests upon the ends of 'the arms 30 and is positioned in contact with the inner surface of the guide element l3. Another air bafile 40 is provided which rests upon the peripheral edge portion of the fire screen 34. The air baflle 40 as best seen in Figure 3, is provided with a central air opening 42 which is spanned by supporting arms 44 which in turn have clips 46 struck out therefrom. In addition to the clips 46 struck out from the material of the supporting arms 44, additional clips 48 are struck out from the otherwise imperforate annular portion 50 of the bafile 40.

Resting upon the peripheral portion of the air bafile M! is a spider structure 54 comprising a plurality, of upstandingarms 56, the upper portion of which extend inwardly and are provided at their ends with spaced upstanding fingers 58 for the reception of a ceramic grid 66 for supporting heating elements 62. Preferably, the grid 60 is in the form of a cross and is provided .with two notched plates shaped to interfit and to extend at right angles to each other. Heating elements (not shown) supported in openings 62 extend between adjacent sections of the cross thus formed and preferably are in the form of electrical resistance heating elements.

Also resting upon the peripheral portion of the air baflie 40 is a generally cylindrical member 55 constituting the heating chamber wall. The member 55 is provided with a plurality of openings 61 adjacent its top and is provided with an inturned radially extending flange 69 at its top on which is supported a cover member preferably provided with suitable heat insulation such as asbestos as indicated at 12, The cover 10 is provided with a central air inlet opening 1'4.

Referring now to Figure 2 there is illustrated an air exhaust or outlet opening 80 provided in the side wall of the casting l0 below the foraminous support 25. At the outside of the casting I0 is a flange 82 for connecting a pipe or stack connection 84 thereto. A best seen in Figure l the flange 82 is of incomplete annular form. It is provided with a shoulder 85 (Figure 2) against which the pipe 54 seats, the shoulder 86 being spaced such that an air inlet opening 88 is provided permitting flow of room air into the stack connection 84. This is for the purpose of providing for substantial uniformity of flow of air through the drier, independent of atmospheric conditions which may affect the natural draft available in the stack to which the pipe 84 is connected.

The operation of the device results in air being drawn downwardly through the openings 19 in the cover and discharged radially outwardly from the blower 22. This establishes air pressure within the casing l4 surrounding the air heating chamber constituted by the shell 55 and the cover Til. Asa result of this increased air pressure air flows in through the opening M in the cover it and also through the side openings 67 into the interior of the air heating chamber. In addition, air will flow circumferentially in the annular space provided between the wall 65 and the casing l4, thus cooling the exterior wall of the casing l4.

Heated air flows downwardly through the central opening 42 in the air baifie 40. It is thence caused to flow generally radially outwardly so as to emerge from the peripheral opening 32 provided in the air baiile 28. Duringits passage the air is caused to flow through the fire screen 34 which as above described, is disposed generally in the form of an inverted cone. The air as it emerges into the drying chamber through the openings 32, moves downwardly over the walls 28 thus affording quick and direct heating of these walls. At the same time the air pressure within the drying chamber thus is elevated and the air flows through the foraminous support and thence outwardly through the exhaust opening 88 and pipe 84.

The temperature of the air is controlled by suitable electrical control mechanism (not shown) under the control of a temperature responsive element of expanding fluid type having a coiled tubular fluid containing element 90 having convolutions disposed generally across the air opening 42 so as to be directly responsive to the temperature of air as it emerges from the air heating chamber.

A suitable access door (not shown) is provided in the side of the drying chamber and preferably is constituted by a hinged portion of the casting H] to which is secured a corresponding shaped portion of the shell 26.

The heat capacity of the electrical heating element 62 is relatively large so that when the drier is first turned on, it quickly reaches operating conditions. Accordingly the necessity of a long period during which the drying oven is coming up to operating conditions is avoided and the electrical heating elements and blower need be energized for only the time which the oven is in use.

Inasmuch as room air is caused to flow through the oven without recirculation, the drying cycle is reduced since vapors once removed from the material by drying are not recirculated therethrough. Moreover, by the provision of the stack connection 84 and the exhaust 88 the escape of obnoxious vapors into the room is completely avoided.

There is thus provided a laboratory drying oven in which a drying chamber is provided with heated dry air under pressure which flows down against samples supported on the foraminous support element 25. The drying oven is designed so that speed of drying is one of its principal advantages, together with the fact that it reaches operating conditions within a very short interval after it is energized.

The oven is useful in quickly removing moisture from any samples or specimens desired. Thus, for example, it is particularly useful in removing moisture from soap, gravel, coal or other material. Since the temperature of the air is under accurately regulated thermostatic control it may be employed to remove moisture from organic or other material which might be injured by excessive temperatures.

The drawings and the foregoing specification constitute a description of the improved laboratory drying oven in such full, clear, concise and exact terms as to enable any person skilled in the art to practice the invention, the scope of which is indicated by the appended calims.

What we claim as our invention is:

1. A laboratory drying oven comprising a ver tical casing, a blower adjacent the top of said casing to blow air downwardly in said casing, a heating chamber in said casing having side walls spaced inwardly from the sides of said casing and a centrally open top wall, the side walls of said chamber having lateral openings therein, a drying chamber beneath said heating chamber, the side walls of said drying chamber being spaced inwardly from the sides of said casing, a partition intermediate said heating chamber and said drying chamber, said partition being imperforate throughout its central portion and having openings adjacent its periphery for downward flow of heated air adjacent the inner surfaces of the side walls of said drying chamber, an air pervious support at the bottom of said drying chamber for supporting material to be dried, an exhaust vent at the side of said casing below said drying chamher, an exhaust pipe connected to said vent, said vent and pipe providing an inlet opening for room air.

2. A laboratory drying oven comprising a vertical casing, a blower adjacent the top of said casing to blow air downwardly in said casing, a heating chamber in said casing having side walls spaced inwardly from the sides of said casing and a centrally open top wall, the side walls of said chamber having lateral openings therein, a drying chamber beneath said heating chamber, the side walls of said drying chamber being spaced inwardly from the sides of said casing, a partition intermediate said heating chamber and said drying chamber, said partition being imperforate throughout its central portion and having openings adjacent its periphery for downward flow of heated air adjacent the inner surfaces of the side walls of said drying chamber, an air pervious support at the bottom of said drying chamber for supporting material to be dried, an exhaust vent at the side of said casing below said drying chamber, an incomplete annular flange of considerably greater diameter than the vent opening partially surrounding said vent opening, an exhaust pipe on said fiange, the incomplete annular flange providing an air inlet opening into the pipe outside of said casing.

3. In a drying oven, a heating chamber and drying chamber, means for forcing air through said chambers, a pair of spaced air baffles intermediate said chambers, the first baflle adjacent said heating oven being imperforate adjacent its edge and having a central air passage, the second bafile being imperforate in its central portion and having a generally annular air passage adjacent the side wall of said drying chamber, a fire screen intermediate said bafiles, means securing the central portion of said fire screen to the central portion of said second baflle, and means securing the peripheral portion of said fire screen to the peripheral portion of said first baffle.

4. In a dryer, a heating chamber, a drying chamber, a partition between said chambers having an imperforate peripheral portion and provided with a central opening for the flow of air therethrough, said partition having supporting arms extending across the opening, clips struck out of the material of said arms, a temperature responsive element including a tubular element a portion of which is coiled to overlie the opening, said clips being bent over to secure the coiled portion of said element to said arms.

5. A drying oven comprising a vertical cylindrical base having an annular supporting flange adjacent its bottom, an internal annular guide flange and an external seat at its top, a foraminous supporting partition and a tubular member on said supporting flange, the upper end of said tubular member being received within said guide flange, said tubular member intermediate its top and bottom being spaced inwardly from said base, an air bafiie mounted on the top of said tubular member, an air heating chamber mounted on the top of said tubular member, a cylindrical casing mounted on said external seat spaced laterally outwardly from said air heating chamber and extending thereabove, air heating means in said air heating chamber, air inlet ports adjacent the upper portion of said air heating chamber, and a blower in said casing above said air heating chamber to force air downwardly through said air heating chamber, said tubular member and said foraminous partition.

6. A laboratory drying oven comprising a drying chamber having a foraminous bottom closure, an air heating chamber disposed over said drying chamber having heating elements therein, an air baflle between said air heating chamber and drying chamber having an imperforate central portion and air flow ports at its periphery for directing air downwardly against the sides of said drying chamber, a blower for forcing air into said air heating chamber adjacent its upper portion,

and air exhaust means below said foraminous bottom closure including a conduit leading to exhaust, and a port adjacent said foraminous support providing for inlet of room air into said conduit.

7. In a drying oven, a heating chamber and drying chamber, means for forcing air through said chambers, a pair of spaced air bafiles intermediate said chambers, the first bafiie adjacent said heating oven being imperforate adjacent its edge and having a central air passage, the second baflle being imperiorate in its central portion and having a generally annular air passage adjacent the side wall of said drying chamber, a generally conical fire screen intermediate said baffles,

and means retaining said baffies and fire screen in assembled relation with the central portion of said fire screen engaging the central portion of said second baflie and with the peripheral portion of said fire screen engaging the peripheral portion of said first bafile.

8. In a drying oven, a heating chamber and drying chamber, means for forcing air through said chambers, a pair of spaced air bafiles intermediate said chambers, the first baflle adjacent said heating oven being generally flat and imperforate adjacent its edge and having a central air passage, the second baffie having a generally flat imperforate central portion and a plurality of spaced legs extending angularly from the plane of said central portion and outwardly from the edge thereof and defining peripheral air passages therebetween, said bafiies being assembled together with the outer ends of the legs of said second baffle directly adjacent the peripheral portion of said first bafile to space the central portions of said baffles apart, a generally conical fire screen intermediate said baflies, the peripheral portion of said fire screen being interposed between the outer ends of the legs of said second baflle and the peripheral portion of said first bafile, and the central portion of said fire screen engaging the central portion of said second baflie.

HARRY W. DIETERT. JOHN A. SCHUCH. RALPH E. STEINMUELLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,326,957 Norwood Jan. 6, 1920 1,752,797 Hutchinson, Jr Apr. 1, 1930 2,080,168 Dietert May 11, 1937 2,313,933 Goerg Mar. 16, 1943 2,414,502 Willcox Jan. 21, 1947 FOREIGN PATENTS Number Country Date 336,679 Great Britain Oct. 20, 1930 492,910 Great Britain Sept. 29, 1938 844,901 France May 1, 1939 

